The History of Bendectin
When bad things happen to good medicines
Bendectin was a combination of Vitamin B6 (pyridoxine) and an antihistamine, doxylamine. It is still marketed in Canada as the drug, Diclectin. In 1983 its manufacturer, weary of defending it, voluntarily removed it from the market. Its bad rep was much more of a populist uprising, fueled by tabloid accusations of deforming babies; scientifically, it could never be proven that it caused any more developmental defects than were present in the general population (defects were no greater in Bendectin users than in non-Bendectin users). But the witch hunt and mob frenzy prevailed, and Bendectin is no longer available in the USA, except by a little creative alchemy (see below). Personally, I miss the stuff. I used it before 1983, and it really helped a lot of my patients. Other antihistamines have been used for nausea as well, by calming the labyrinthine inner ear.
So what are we left with?
Emetrol – An over-the-counter mixture of sugar syrups and phosphoric acid (phosphorylated carbohydrate solution), it acts by soothing the actual wall of the gastrointestinal tract. But since hyperemesis more than likely originates in the head, not the stomach, it may help – but it may not.
Compazine (Prochlorperazine) and Phenergan
(Promethazine) – these are phenothiazine-like drugs, meaning that they act centrally in the brain to relieve nausea. Technically, they’re sedative-antihistamines, like the doxylamine in the old Bendectin.
An allergic reaction to phenothiazines is not like in other drugs. With other drugs, one may develop hives. But with phenothiazine reactions, there can be abnormal eye movements, protruding tongue, a feeling of tongue thickness and with it difficulty speaking. You’ll wonder if you’re having a stroke.
Called oculogyric symptoms, this presentation will worry a patient greatly (understandably so!) until a trip to the
ER for a Benadryl shot – the same thing for hives – which will usually cure the problem.
Tigan (Trimethobenzamide) is an actual antiemetic (anti-nausea medication), probably related to anesthetics.
Zofran (Ondansetron) is a newer very powerful antiemetic, the exact mechanism of action unknown. But it has no real toxic levels and doesn’t seem to interact badly with other drugs. It’s used to great effect for nausea after surgery. It is extremely expensive. (You get what you pay for!)
Wait a minute! I’m pregnant! These are drugs!
FDA Drug Risk Categorizations
The FDA has a categorization of drug risk to the fetus that runs from “Category A” (safest) to “X” (known danger – don’t use!):
- Controlled studies in women fail to demonstrate a risk to the fetus in the first trimester (and there is no evidence of a risk in later trimesters), and the possibility of fetal harm appears remote.
- Either animal-reproduction studies have not demonstrated a fetal risk but there are no controlled studies in pregnant women, or animal-reproduction studies have shown an adverse effect (other than a decrease in fertility) that was not confirmed in controlled studies in women in the first trimester (and there is no evidence of a risk in later trimesters).
- Either studies in animals have revealed adverse effects on the fetus (teratogenic or embryocidal or other) and there are no controlled studies in women, or studies in women and animals are not available. Drugs should be given only if the potential benefit justifies the potential risk to the fetus.
- There is positive evidence of human fetal risk, but the benefits from use in pregnant women may be acceptable despite the risk (e.g., if the drug is needed in a life-threatening situation or for a serious disease for which safer drugs cannot be used or are ineffective).
- Studies in animals or human beings have demonstrated fetal abnormalities, or there is evidence of fetal risk based on human experience or both, and the risk of the use of the drug in pregnant women clearly outweighs any possible benefit. The drug is contraindicated in women who are or may become pregnant.
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